This invention relates to improvements in structural frame embers and assemblies, and more particularly to improvements in frame members and assemblies for use in conjunction with machines requiring electrical circuit interconnections, and still more particularly to improvements in frame members and assemblies of the type which are capable of conducting electrical signals, voltages, and the like, to and from the circuitry of an associated machine.
Although the invention has wide applications, as will become apparent, a preferred embodiment of the invention is particularly suitable for applications in electrostatographic reproducing machines. In a typical electrostatographic reproducing machine, a photoconductive insulating surface, often in the form of a moving belt, is uniformly charged and exposed to a light image from an original document. The light image causes the exposed or background areas to become discharged, and creates an electrostatic latent image on the surface corresponding to the image contained within the original document. Alternatively, a light beam such as a laser beam may be modulated and used to selectively discharge portions of the photoconductive surface to record the desired information thereon. The electrostatic latent image is made visible by developing the image with a developer powder, referred to in the art as toner, which may be subsequently transferred to a support surface such as paper to which it may be permanently affixed by the application of heat and/or pressure.
In these commercial applications, it is of course necessary to distribute electrical power, high voltage and/or logic signals between the various units, subsystems, customer replaceable units and/or cartridges of the machine. Traditionally, this has been accomplished utilizing conventional wires and wiring harnesses in each machine to distribute power and logic signals between, for example, the main processor and frame of the machine and a removable processing unit. For instance, conventional plug and socket arrangements have been used which can be either manually connected or joined automatically on insertion of the unit into the main processor. Such automatic joining requires precision positioning and alignment of the unit on insertion with very low tolerance for error. Typically locating members such as pins or rails are used to insure proper positioning, all of which adds to the manufacturing cost of the machine. In addition, conventional wires and wiring harnesses are flexible and therefore, do not lend themselves to automated assembly such as with the use of conventional robots further leading to increased manufacturing costs.
In many typical copier systems, flexible interconnects have been accomplished by such techniques as flexible ribbon wires with plugs that attach to mating plugs on the members to be interconnected. Such ribbon wiring arrangements, however, do not lend physical support between the interconnected members, and also often involve intensive labor fabrication requirements. Furthermore, such harnesses may have to be handled or moved several times to make all connections required. This is a highly labor intensive task, frequently requiring routing of the several harnesses through channels and around components manually with the final connections being also accomplished manually, thereby resulting in potential human error in the assembly, which might be reduced with the use of automated and in particular robotic assembly. Conventional harnesses also often require chafe protection, standoffs, and tie wraps which further add to the assembly and installation costs. In addition to the relatively high labor costs associated with electrical harness construction and installation, it is well to note that such wiring harnesses are less than totally reliable in producing their intended function. Furthermore, and with increasing sophistication of the capabilities of such products, a plurality of wiring harnesses may be required in any individual machine which can require a large volume of space thereby increasing the overall size of the machine. Accordingly, there is a desire to provide an alternative to the conventional wiring and wiring harnesses that overcomes these difficulties.
One of the considerations for the development of wiring harnesses and interconnects in electrostatic copier environments is the relatively hostile machine surroundings having surfaces possibly contaminated by dirt, toner, silicone oil, or other debris. Furthermore, metal contacts that might be used often tend to oxidize forming an insulating layer on the contact surface thereby further degrading the reliability and performance of the contact and of the machine. Such contacts, therefore, need to be either improved or minimized.
To address these and other problems, and with recent emphasis toward the goal of replacing conventional wire harnesses in copier products to achieve a so-called "wireless copier", what is needed is the incorporation of circuit functions directly into large structural machine parts. For example, the surfaces of machine covers, frames housings, support brackets, bases, and the like, can all provide vacant "real estate" for circuitization, given that the substrate materials are, or can be made, insulating and can be appropriately "circuitized".
New manufacturing processes are likely to be required for efficient and economical patterning, plating, and component loading of the large multifunctional parts envisioned for copiers of the future. Also required will be new materials and methods to construct key structural members.
What is needed is the identification of new materials and fabrication techniques by which structural frames having integrated electrical interconnect features can be provided.